<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>数组去重</title>
</head>

<body>

</body>
<script>
    let arr = [1, 1, 2, 2, 3, 4, 5, 2, 1, 4, 5, 3]
    for (let i = 0; i < arr.length; i++) {
        for (let j = i + 1; j < arr.length; j++) {
            if (arr[i] == arr[j]) {
                arr.splice(j, 1)
                j--
            }

        }
    }
    console.log(arr);
</script>

</html>